Pneumatic hammer.



Patented Feb. 6, 190 0.

J. W. JDHNSUN.

PNEUMATIC HAMMER.

(Applicatlon filed June 2, 1899.)

(No Model.)

w- Mum/ atko'cmuz WWI/wow UNiTED STATES PATENT OFFICE.

JOHN W. JOHNSON, OF BURLINGTON, VERMONT.

PNEUMATIC HAMMER.

SPECIFICATION forming part of Letters Patent No. 643,063, dated February 6, 1900.

Application filed June 2, 1899. Serial No. 719,103. (No model.)

T0 at whom it may concern.-

Be it known that 1, JOHN YV. JOHNSON, a citizen of the United States, residing at Burlington, in the county of Ohittenden and State of Vermont, have invented certain new and useful Improvements in Pneumatic Hammers; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to improvements in pneumatic hammers, and pertains to a tool especially adapted for use in delivering a blow to a chisel for smoothing and cutting stones.

One object of my present invention is to increase the blow and the rapidity of the operation of the tool by providing supply-channels for moving the tool up and down, the said channels being of relatively different sizes and capacities and also provided with an increased intermediate portion, forming a storage-space for the air, steam, or liquid which may be used for the operation of the tool.

Another object of my present invention is v to so construct the tool that the chisel is independent of the piston which delivers the blow, but is actuated by the movement of the stem of the piston, and which enables me to regulate the blow delivered to the chisel by holding with the hand the chisel, and thus regulating the distance the tool will reciprocate, as will be more fully explained hereinafter.

Referring now to the accompanying drawings, Figure 1 is a central longitudinal sectional view showing the piston in the position assumed thereby when in its upward limit of movement. Fig. 2 is a similar view showing the position assumed by the piston when in the limit of its lowest movement. Fig. 3' is a similar view showing the piston at an intermediate point within its cylinder. Fig. 4 is a longitudinal sectional view taken at right angles to Fig.1, the piston being removed and looking in the direction indicated by arrow, Fig. 1. Fig. 5 is a sectional View taken on the line 5 5, Fig. 1, and longitudinal the feeding-passages. Fig. 6 is a transverse sectional view taken on the line 6 6 of Fig. 1.

Referring now to the drawings, A indicates a cylinder, which will be of any desired form or size, the said cylinder preferably composed of a cylinder 2 and the two end pieces 1 and 3, screwed in the ends of the cylinder. Formed in the wall of the cylinder at a point about equidistant from the ends of the limit of movement of the double-headed piston a is a supply-port S.

Formed in the wall of the cylinder and extending longitudinal thereof are the two U- shaped passages or ports E and F, the one F having an upper outlet 0' to the cylinder and a lower inlet 0. The lower passage or port E is provided with an upper inlet B and a lower outlet B to said cylinder. Formed also in the wall of the cylinder and preferably, though not necessarily, at the opposite side thereof is an exhaust-passage K, having a direct outlet D with the upper end of the cylinder and a lower outlet 61 for the lower end of the said cylinder. The exhaust D is provided with a valve 0, by means of which the speed of the tool can be regulated.

The passage-way or port F supplies the pressure for forcing the tool downward, and the passage-way or port E supplies the pressure to the lower end of the cylinder for moving the piston upward, and especial attention is directed to the fact that the passage F and its inlet-ports O and O are of a larger area than the passage-way E and its inletports 13 and B. The relative difference in size may vary according to the force desired in the downward stroke of the tool; but preferablyI make the area or capacity of the upper passage-way and its ports double that of the lower passage-way and its ports. Attention is also directed to the fact that the passage-ways E and F are increased in their size between their inlet-ports, which constitutes what I term storage spaces or chambers, for a purpose to be hereinafter described.

The piston or consists of two piston-heads e, one at each end thereof, forming between them an annular space N, the said space N being at all times in communication with the supply-port S of the cylinder, and this space N forms what may be aptly termed a supply-chamber for the passages E and F.

Formed in the upper and lower ends of the cylinder heads e are the circumferential grooves f, which serve a purpose to be presently explained. Projecting from the lower head of the piston is a stem G, which fits snugly the longitudinal bore or passage II, formed in the elongated lower end I of the cylinderA. This stem Glis preferably about half the length of the bore or passage-way H for the purpose of permitting the reception of the upper end 9 of tool h. This stem 9 of the tool 7t also fits smoothly the bore H, and the upper end of this bore H is provided with a circular or circumferential groove P, the function of which will be hereinafter stated.

In operation the pressure is supplied through the opening S to the supply space or chamber N between the two heads of the piston, and as it bears with equal force against the adjacent faces of these heads there is no tendency of the pressure to force the piston in either direction, as will be readily understood. The piston in Fig. 1 is shown in its uppermost position and which is slightly out of contact with the upper end of the cylinder, whereby pressure passes through the port 0 from the supply space or chamber N to the upper end of the cylinder, and thus forces the piston downward until the lower edge of the upper head of the piston closes the port 0 of the passage-way F, and then the port B of the passage-way E is opened, establishing communication between the supply-space S and the lower end of the cylinder for forcing the piston upward.

For the purpose of causing the piston to travel the full length of a stroke I enlarge the passage-ways E and F intermediate their ends for the purpose of forming a storage-space for the pressure. This enables the pressure which has been stored in the passage-way F to force the piston to the limit of its lowest position before the pressure has filled the storage-space of the passageEand has passed into the lower end of the cylinder in sufficient quantity or with sufficient pressure to overcome the pressure of the supply to the upper end of the cylinder. This operation is reversed in the upward movement of the piston, and in the storage or supply space,

owing to the enlargement of the passage-way F and its contracted outlet, the pressure is delayed in forming at the upper end of the cylinder sufficiently to prevent the pressure in the lower end of the cylinder carrying the piston to the limit of its upward movement. In this way I am enabled to get the full stroke of the piston within the cylinder, andits movement is not immediately interrupted when the respective passage-ways are opened to establish communication with that end of the cylinder toward which the piston is passing.

Owing to the increased area of the passageway F and its outlet-ports C and O as compared with the passage-ways E and its outlet-ports, I obtain about twice the power in the downward movement or blow of the pis ton as is obtained in the upward movement,

as will be readily understood, owing to the fact that the difference in capacity is about two to one. The difference between the force of the upward and lower movements of the piston will be regulated by the relative variation in the passages E and Fand their inletports.

The chisel being separate from the piston, a suction in the upward movement of the stem G of the piston will draw the tool up with it, and this suction is increased by the groove P, which forms practically an air-tight joint. When the .tool is permitted to travel the full length of its movement by the suction of the stem G, the heaviest blow is delivered to the tool. When it is desired to regulate the blow of the piston to the tool, it is only necessary for the operator to grasp the tool and to hold it in contact with the stone being acted upon, and thus preventing it from following the piston and delivering a dead blow to the tool instead of an accelerated blow, which is delivered when the tool is permitted to travel back and forth with the piston, owing to the said suction action. The suction, while sufficient to raise the tool,does not prevent it from falling easily, there being sufficient space to prevent or break the compression of air between the piston M and the tool when the former is moving outward. In this way I am enabled to deliver a heavy blow, which will quickly smooth the rough portion intermediate the edges of the block of stone, while at the same time I am enabled to regulate and to deliver a light blow to the edges of the stone, and thus prevent chipping thereof.

The grooves f, formed in opposite ends of the piston-heads, and also the groove P in the bore 0r passage H are filled with liquid, thus forming air-tight passages, which takes the place of the usual packing, and this liquid packing relieves the wear upon the parts and lengthens the life of the tool.

The exhaust-port D at the top of the cylinder has a direct outlet governed by a handvalve which lets out double the amount of air or liquid (supplied by F) used to move the hammer or piston downward in order to reduce the amount of liquid above the piston sufficiently so that when the piston starts to move upward it will do so readily, whereas if the liquid were retained above the piston and which is supplied from F (of double the capacity of E) the small amount of force expended from E (being only'about one-half that of F) would make it impossible for the piston to be moved upward. The exhaustport D is therefore provided to let out the liquid, so that there will be comparatively little resistance to the movement of the piston upward.

Having thus described my invention, what I claim, and desire to secure by Letters Patent, is

1. A tool of the character described comprising a cylinder, a double-headed piston therein, the cylinder having a supply-port in communication with the space between the head of the piston, feed passage-ways having communication respectivelywith the opposite ends of the cylinder and with the space between the heads of the piston, said passageways having storage-chambers at points intermediate their ends, substantially as described.

2. A tool of the character'described, comprising a cylinder, a double-headed piston therein, the cylinder having a supply-port in communication with the space between the heads of the piston, feed passage-ways having communication respectively With opposite ends of the cylinder and with the space between the heads of the piston, the said passage-ways being enlarged between theirends to furnish storage spaces or chambers, substantially as and for the purpose described.

3. A tool of the character described comprising a cylinder, a double-headed piston therein, the cylinder having an inlet-port in communication with the space between the heads of the piston, the cylinder having also elongated feed passage-ways incommunication respectively with opposite ends of the cylinder and with the space between the heads of the piston, said passage-ways being enlarged between their ends to constitute storage spaces or chambers, and the upper passage-way having its inlet and outlet ports of greater area than the corresponding ports of the lower passage-way, substantially as described.

4. A tool of the character described comprising a cylinder, a double-headed piston therein, the cylinder having a supply-port in communication with the space between the heads of the piston, feed passage-ways having communication respectively with opposite ends of the cylinder and with the passage between the heads of the piston, the inlet and outlet ports of the passage-ways being elongated in a direction transverse the cylinder and the said passage-ways being enlarged at points between their ports to constitute storage spaces or chambers, substantially as de scribed.

In testimony whereof I affix my signature in presence of two witnesses.

JOHN W. JOHNSON.

Witnesses:

HENRY J. JOHNSON, GILBERT A. Dow. 

